A selective reduction catalyst device (SCR) is provided as one of exhaust gas purification treatment devices in an exhaust passage of an internal combustion engine such as a diesel engine mounted on a vehicle (for example, see Patent Document 1). The selective reduction catalyst device (SCR) is a device that reduces and purifies NOX contained in exhaust gas with ammonia (NH3) generated by hydrolyzing urea water injected toward the exhaust gas from a urea water supply device provided in the exhaust passage on an upstream side by heat of the exhaust gas.